1. Technical Field
This invention relates to insulation and electrical components that utilize electrical insulation for use in a liquid environment in general, and to electrical transformers and components thereof that utilize electrical insulation in an oil environment in particular.
2. Background Information
Current standard insulating materials in liquid filled transformers are cellulosic materials of various thicknesses and density. Cellulose-based insulating materials, commonly called Kraft papers, have been widely used in oil-filled electrical distribution equipment since the early 1900's. Despite some of the shortcomings of cellulose, Kraft paper continues to be the insulation of choice in virtually all oil-filled transformers because of its low cost and reasonable performance. It is well known, however, that cellulosic insulation in an oil environment is subject to thermal degradation and vulnerable to oxidative and hydrolytic attack.
U.S. Pat. No. 8,193,896 and U.S. Patent Publication No. 2014/0022039 describe heat stabilized aliphatic polyamide materials that can be used as an electrical insulation within liquid filled electrical transformers. Testing of the heat stabilized aliphatic polyamide materials described in these documents has established that they perform very well when used in a cellulose-free application; e.g., when 100% of the insulating materials within an electrical transformer are formed from the aforesaid heat stabilized aliphatic polyamide materials.